1. Field of the Invention
The present invention relates to a photomask positioning apparatus and more particularly to a photomask positioning apparatus for a photomask box comprising a positioning device and a holding device in a containing space of a lid such that the photomask can be positioned between the positioning devices and the holding devices at two sides of the containing space to facilitate a robotic arm to take out the photomask without frictions with the fixing devices so that damage to the photomask can be reduced.
2. Description of the Related Art
After entering into the 21st century, humans life is entering into a field of a digital era. Nowadays, many articles and tools in humans life are substituted substantially by digital high technical products and making people have more conveniences and enjoy the civilized advances of the high technologies. However, in the digital era, most electronic products and tools are related to digital technologies or are controlled by high technical IC chips to achieve the objectives of quickness and automation. Therefore, people living in the digital technical field era have to control a variety of high technical technology products and tools by further improved digital knowledge and skills. Wherein the high technological IC chips are very important elements. Since IC chips are constituted of very high precision integrated circuit, and its manufacturing processes are using high precision machines to perform high precision  integrating processes on silicon wafers by using photomasks in an environment of a clean room. The machines, manufacturing factories and manufacturing cost are very expensive. Therefore, in the process of manufacturing wafers, yield factors of the products can determine whether a semiconductor factory can profit. Thus, raising the yield factors of the products is the most important subject of every manager of the semiconductor factories.
The objective of the SMIF system is to reduce particles flux in warehousing and transportation processes of a semiconductor process. The method to achieve this objective partly comprises ensuring gaseous medium (e.g. air or nitrogen) surrounding the wafer relative to the wafer is basically fixed in warehousing and transportation processes and ensuring particles in a surrounding environment do not enter an environment surrounding to the wafer. The SMIF system is capable of using little gas without particles to provide a clean environment for articles. The activation, airflow direction, and outside pollution of the gas are all need to be controlled.
However, to avoid wafers or photomasks from damaging, the photomask boxes are used to transport wafers or photomasks. Besides, limiting device are set in the photomask boxes to limit the positions of the photomasks to prevent the photomasks from shifting because of shaking or other factors in transporting process to damage the photomasks. However, since robotic arms are used to take or move the photomasks in the wafer manufacturing process, the limiting devices cannot totally limit the moving ranges of the photomasks in the photomask boxes, and a predetermined moving space has to be preserved between the photomask and the limiting device. Besides, to prevent the photomasks from shifting when the robotic arms take the photomask, and the photomask cannot be accurately placed onto the robotic arms. Referring to FIGS. 9 and 10, a blocking mean B1 set at one side in a lid B comprises a plurality of levers B2. An activating element B3 is set at the other side of the plurality of levers B2. A depending element B4 is fixed on the activating element B3. When the lid B covers on a substrate C, the depending element B4 is positioned against a side of a photomask board C1 on the substrate C so that the photomask board C1 can be properly positioned. However, when using aforementioned photomask box A, there are still many shortcomings described.
1. When the depending element B4 is positioned against the side of the photomask board C1, they generate micro-fragments in friction processes to pollute and damage the photomask board C1.
2. When the blocking means B1 uses the plurality of levers B2 to connect the activating element B3, the micro-fragments will be generated easily because of friction in a contacting area between the levers B2 and the activating element B3.
3. When the blocking means B1 closes the lid B using the substrate C, the activating element B3 contacts the substrate C to move upward and rightward to achieve the function of the depending element B4 against the photomask board C. The micro-fragments will be generated at the activating element B3 contacting with the substrate C because of the opening/closing, shaking of the photomask box A and frictions during transport action.